This invention relates to hinges, and has particular application to butt hinges for doors or windows.
Butt hinges are generally formed from a pair of substantially rectangular flat metal strips joined together about a pivot axis so that the two or more leaves of the hinge abut one another in face to face contact when the hinge is closed. Such hinges are difficult to locate accurately, requiring precise measurements on both the door and the jamb, and in addition require rebates to be formed in both the door and the jamb to receive the leaves to enable the door to close snugly against the jamb. Nevertheless, it frequently occurs that such fittings require the edge of the door to be trimmed or bevelled to prevent binding when the door is closed.
A significant improvement over this type of butt hinge, has been the provision of a pair of overlapping pivotally connected leaves fitting one within the other to present substantially one leaf thickness when the hinge is closed. This type of hinge is typically formed with an inner leaf nested within an outer or surrounding leaf, with each leaf being of uniform thickness so that when the hinge is closed each leaf lies within the same plane thereby presenting a hinge of only one leaf thickness. Examples of these hinges are shown in New Zealand Pat. No. 101,637 (Hurcal Engineering Company Ltd.) and U.S. Pat. No. 4,237,557 (Chapel). Neither of these constructions overcomes the problem of binding when the door is closed, and thus it is necessary to trim or bevel the edge of the door to prevent binding.